IL10 and Allergy: IL‐10 production by CD4+CD25+ allergen‐specific Tr1 (regulatory T) cells, B cells and monocytes induces and correlates with the production of IgG4 and the increase in IgG4/IgE ratio in allergen and peptide immunotherapies in allergy and autoimmune diseases 60, 61, 62 and are thought to underlie the induction of tolerance to allergens 63.